August 1, 2012
Solar Winds Affect Earth’s Magnetosphere
April Flowers for redOrbit.com — Your Universe Online
Weather has always affected our lives, but we are increasingly reliant on technology that can be disrupted by space weather.Geomagnetic storms, which are major disturbances of the magnetosphere, cause high altitude flights to be rerouted, costing many thousands of dollars per flight; cause GPS errors of up to 151 feet; and affect the International Space Station and satellites.
Geomagnetic storms and other space weather disturbances are caused by the solar wind. Hot plasma from the Sun interacts with Earth's magnetic field creating the wind. Although scientists study the wind, they have largely ignored the fact that solar wind contains layers of very strong velocity shear, so they have no understanding of how this shear affects space weather.
Joseph E. Borovsky, from the Space Science Institute in Boulder, Colorado, combined statistical analysis of solar wind data from the Advanced Composition Explorer (ACE) satellite with magnetohydrodynamic simulations, which are used to study the dynamics of electrically conducting fluids like plasma, to characterize the properties of the shear layers in the solar wind and Earth's reaction to them.
The ACE satellite measures solar particles and gives nearly 24/7 information about solar wind activity. It is part of NASA's Explorer program and orbits the earth approximately 1.5 million kilometers from Earth at the L1 liberation point, that place where Earth's gravitational pull is in equilibrium with the Sun's. The satellite should stay in orbit until 2024.
Published in Journal of Geophysical Research-Space Physics, Borovsky's study finds that as many as 60 shear zones pass Earth every day at velocities above 31 miles per second disturbing the entire magnetosphere and ionosphere. These disturbances could cause a comet-like disconnection of the Earth's magnetotail, a tail like extension of Earth's magnetic field on the side facing away from the Sun. Velocity shears do not cause geomagnetic storms, but they may just determine how such a storm works.